TanDEM-X DEM Calibration Status and Commissioning Phase

Abstract

TanDEM-X is the first bistatic space-borne SAR mission. It will be formed by adding a second, almost identical spacecraft to TerraSAR X and flying them in a closely controlled formation. The primary goal of the mission is the derivation of a high-precision global Digital Elevation Model (DEM) according to HRTI level 3 quality. In order to fulfil the required height accuracy, height references have to be applied in the calibration of the DEM, together with a least squares adjustment of adjacent interferograms. To validate the DEM calibration concept, the simulated height error models and the accuracy of the selected height references, several activities have been planned to be performed until launch of TanDEM X and during the commissioning phase right after. The commissioning phase of TanDEM X will follow the philosophy and profit from the experience of the successful one of TerraSAR X. However, a higher complexity will be added in this case due to several aspects. On the one hand, the monostatic commissioning phase will be more compressed in time than the TerraSAR X one, due to the demanding schedule for the global DEM acquisition. On the other hand, new analyses have to be performed concerning the bistatic calibration, as well as the validation of the synchronisation link and the exclusion zone selector. Content of this paper is the description of the general DEM calibration concept of TanDEM X, the results of the validation activities and the interferometric experiments and a brief draft of its monostatic and interferometric commissioning phase plan.